There are two basic families of cabinet drawer and door locks: deadlocking and latch locking types of locks and cam-type locks. Both families of locks are used on cabinet drawers and doors such as those found on office desks, credenzas, and interior cabinetry. In the former family, an elongated bolt moves in a reciprocating manner into and out of a bolt housing between locked and unlocked positions, respectively, upon actuation of a key. In the latter family, an elongated bolt moves along an arcuate path, between locked and unlocked positions. In the cam family of locks, an angular rotation of 90 degrees is typically sufficient to determine the locked and unlocked positions.
Both families of locks may have their bolts actuated by either pin tumbler cylinder and plug assemblies, or disk tumbler-type assemblies. The disk tumbler-type assemblies are the least expensive and historically have been used in the cam type of lock. A lock of this type is shown in U.S. Pat. No. 3,863,476 to Patriquin in which a plurality of spring-loaded plates in a plug are biased to position a protrusion from the plates into an elongated trough or cavity in an externally threaded lock body. Interference between the protrusions and sidewalls of the lock body trough prevent rotation of the plug. Upon insertion of a key into a keyway of the plug, the plates retract and the protrusions are withdrawn from the trough. Thereupon, the plug can rotate within the threaded lock body. The plug is longitudinally restrained within the lock body by a spring-loaded clip. The bolt is typically journalled for rotation with and screwed onto a longitudinal extension at the rear of the plug. A cam lock of this type is considered a “direct drive” cam lock because the bolt is directly journalled for rotation with the plug. Stated another way, consider a cam lock of the type described in which the lock is received in a desk drawer, wherein the bolt at a 12 o'clock position interferes with a downwardly protruding sill or ledge in the desk. By inserting a key into the plug keyway the disk tumblers are retracted so as to be free of a trough in the externally threaded cylindrical body. Rotation of the key by 90 degrees to the 3 o'clock position clears the bolt of the desk so that the drawer may be opened. The externally threaded, cylindrical lock body may be provided with a pair of internal troughs angularly spaced at 90 degrees with respect to one another so that the key may be withdrawn while the bolt is in the unlocked, 3 o'clock position. Otherwise, to remove the key, the plug must be counterrotated back into the 12 o'clock position leaving the bolt in the “locked position” while the drawer is still open. This procedure has the undesirable consequence in that accidentally closing the open desk drawer with the bolt locked into the 12 o'clock position tends to mar the desk cabinetry. By positioning a second trough in the lock body cavity at the 3 o'clock position, this result can be avoided.
Over the years, it has become desirable to provide cam locks with a pin tumbler rather than a disk tumbler system. In the pin tumbler system, the disk plates are replaced with a series of cylindrical pins, which reside in bores in the plug. These “bottom pins” have differing lengths corresponding to ridges and valleys in a mating key. The lock body or cylinder is provided with a corresponding series of spring-loaded top pins, which can drop down into the bores in the plug into which the lower pins reside. When a key is inserted into the plug keyway, the top pins and bottom pins form a shear line at the interface of the plug and cylinder, allowing the plug to rotate freely. A particular problem with this type of lock is that the key can be inserted or removed only when the top and bottom pins are in alignment (typically the 12 o'clock position). A rekeyable pin tumbler cam lock of this type is shown in U.S. Pat. No. 5,038,589, issued to Martin and assigned to the predecessor in interest to the assignee herein. The disclosure of said patent is incorporated herein by reference. Thus, a cam lock adapted as a pin tumbler lock will suffer from the “damaged desk” syndrome discussed above unless a means is provided for rotating and locking the bolt in respective 12 o'clock and 3 o'clock positions, while permitting continued rotation of the key back to the 12 o'clock position.
For this purpose, the so called “lazy cam” has been developed in which the bolt of a pin tumbler type cam lock is free to rotate about a protrusion extending from a rearward surface of the plug. The lazy cam, however, is journalled for rotation with the plug and drives a pin or other protrusion on the bolt. An opposite side of the bolt is typically also provided with a forwardly extending pin that cooperates with laterally extending shoulders on the rear of the cylinder so as to limit rotation of the bolt through 90 degrees. The above-described structure permits the plug to rotate through 360 degrees while the bolt rotates through only 90 degrees, thus allowing the key to be removed while the bolt remains rotationally contained between the shoulder on the cylinder and a shoulder on the lazy cam. The desk drawer can now be opened and closed with the bolt in the unlocked position with the key removed.
The above-described lazy cam design provides the cam lock with all of the advantages of a pin tumbler design (e.g., ease in rekeying, possible master-keying with other cabinet drawer and door locks as well as entryway locks), which advantages are difficult to achieve or unattainable with disk tumbler-type locks. However, geometric realities prevent the bolt from being positionable anywhere other than the 12 o'clock and 3 o'clock positions described without changing the threaded cylinder body, so as to reposition the shoulders thereon that define the arcuate range of movement for the bolt. Alternate positioning for the bolt is desirable, as consumers have needs for cam locks having bolts that operate between the 12 o'clock and 3 o'clock positions; the 3 o'clock and 6 o'clock positions; the 6 o'clock and 9 o'clock positions; and the 9 o'clock and 12 o'clock positions as in drawer locks, left-hand door locks, tray locks, and right-hand door locks, respectively. A low-cost, rekeyable pin tumbler cam lock (ambidextrous) that addresses this problem is disclosed in U.S. Pat. No. 5,737,950 issued to Yun-Bin and assigned to the assignee herein. The disclosure of said patent is incorporated herein by reference.
Thus, there are now available pin tumbler cam locks having many attributes of entryway cam locks, such as rekeyability, master-keyability, ambidextrous design, etc. However, further integration between the world of pin tumbler cam locks and entryway locks is desirable, particularly in the institutional environment. By way of example, schools, hospitals, and the like frequently have deadlocking entryway doors to classrooms, laboratories, etc. Behind these entryway doors are cabinet doors and drawers for securing biological and chemical materials, pharmaceutical products, and, with respect to casinos and the like, cash drawers. The internal entryway doors of such institutional rooms are typically keyed with so-called standard deadbolt cylinders using spring-loaded pin tumbler designs. As is well known to those of ordinary skill in the art, Schlage manufactured a highly successful standard deadbolt cylinder in which the upper and lower spring-loaded tumbler pins are contained in a unitary body. A rear end of the cylinder is engageable with a driver bar (commonly known as a “tailpiece”) that enabled the deadbolt cylinder to engage a variety of different entryway deadbolt mechanisms. Within the industry, this type of deadbolt cylinder became known by the acronym “SCDC” as a shorthand notation for “Schlage-Compatible Deadbolt Cylinder”. U.S. Pat. No. 5,657,652, issued to Martin, entitled Pin Tumbler Cabinet Door and Drawer Deadlocking Latch Lock”, demonstrates the adaptation of an SCDC (reference numeral 20 in FIG. 4 of said patent) used in conjunction with a deadlocking cabinet door and drawer latch lock. By utilizing identical Schlage-compatible deadbolt cylinders in both entryway doors and cabinet doors and drawers of institutional organizations, a synergistic efficiency is achieved, whereby a locksmith can create one key for a classroom, hospital laboratory, or the like and allow the occupant to use the same key to open the cabinet drawers and doors as well. Nevertheless, adaptation of a standard Schlage-compatible deadbolt cylinder to a cam type of lock in an economically viable design has heretofore eluded the industry.
Therefore, a need exists for an insert cylinder type cabinet cam lock that can utilize a standard Schlage-compatible deadbolt cylinder.